Leap Year

Published on 2/29/2020

Leap Year

Leap year is defined as a year occurring once every four years that has 366 days and includes a February 29th


Leap years can be fun and a time to celebrate special occasions, like birthdays that come once every four years. Some people believe that leap years are bad luck and others believe that being born on a leap day and being a ‘Leapling’ is good luck.


But why do we need an extra day? Adding an extra day each year keeps us aligned with the seasons. Earth’s orbit around the sun takes 365.25 days and we only have 365 days in a year. To make up for the .25 we add the extra day, if we didn’t our seasons would gradually be thrown off. Without having this extra time to our year, the calendar would be off by about 5 hours each year, eventually, in 100 years our seasons would be off by 25 days. Over time it would cause our winters to be during summer months and our summers to be in winter months.


Leap year is an idea that has been used for a couple hundred years, but the concept was created many years ago by the Ancient Romans. The Ancient Roman calendar started by adding an extra month every few years to stay aligned with the seasons, but this didn’t necessarily work. Time was thrown off and not in sync with the seasons, so Julius Caesar introduced the idea of a leap day, similar to what we still do today. However, Caesar added an extra day to the wrong years, and this continued to throw off the seasons.


According to the Old Farmer’s Almanac, there are two rules to leap years:

  1. A year may be a leap year if it is evenly divisible by 4.
  2. Years that are divisible by 100 (century years such as 1900 or 2000) cannot be leap years unless they are also divisible by 400. (For this reason, the years 1700, 1800, and 1900 were not leap years, but the years 1600 and 2000 were.)


If a year satisfies both the rules above, then it is a leap year. 


Emma Zimmerman